how do you know if your saved breastmilk is spoiled?

Cali☀️
I didn't label it while stored in the fridge but it might be 6 days old. When I smell my fresh breastmilk it literally has NO smell. When I smell this breastmilk it has a slight smell but I wouldn't say it smells foul or spoiled. Can I feed to baby now or just toss?